A carbonylation process of a methanol method is known as an industrial method for producing acetic acid. In this process, for example, methanol and carbon monoxide are reacted in the presence of a catalyst in a reaction vessel to produce acetic acid. The reaction mixture is evaporated in an evaporator, and the vapor phase is purified in a lower boiling point component removal column and subsequently in a dehydration column so that product acetic acid is prepared. Alternatively, product acetic acid is prepared via a higher boiling point component removal column subsequent to the dehydration column, and further, a product column (Patent Literature 1, etc.).
In such an acetic acid production process, a distillation column for distilling a crude acetic acid solution containing acetic acid and an impurity having a higher boiling point than that of acetic acid to purify the acetic acid, for example, the dehydration column, the higher boiling point component removal column, or the product column described above, presents the significant problem that the apparatus is corroded. Therefore, an expensive material having corrosion resistance is used, or a corroded part needs to be repaired, leading to increase in equipment cost or maintenance cost.